How to create a complex div from multiple divs?

Question

JavaScript

It is desirable that all this happens at the click of a button.

Answer 1

as usual, createElement / $(tag), but at least shove it into innerHTML, at least use template, there are a lot of options

Answer 2

$('.btn').click(function() {
 $('body').append("<div class='newBlock'></div>");
 for(i=1; i<=10; i++)
   $('.newBlock').append("<div class ='newSubBlock'></div>");
 });